Apparatus including devices of this type are known from the prior art. By way of example, U.S. Pat. No. 6,752,505 granted on 22nd Jun. 2004 in the name of Solid State Opto Limited, discloses a transparent film used as an optical guide for diffusing light homogenous from a quasi-punctual light source. In accordance with this document, optical elements are arranged in the optical guide, possibly randomly, to extract light and direct it to a liquid crystal type display (LCD). The main object of the document is to obtain homogenous illumination with the best possible yield from the light emitted by the light source, the illumination obtained exhibiting a good compromise between clarity and softness, due to optimised diffusion. This patent discloses how diffusion can be optimised because of the distribution of the optical light extraction elements over the entire surface of the optical guide, as a function of the available light sources and the surface to be illuminated.
This type of system can be implemented for lighting an LCD, either by front lighting or backlighting without leading to an excessive thickness of the display device thereby formed. However, the aforementioned document does not provide any other application or use for this type of device.